On Sun, Jun 09, 2019 at 08:14:29PM +0200, Ard Biesheuvel wrote:
On Sat, 8 Jun 2019 at 13:43, Sasha Levin <sashal@xxxxxxxxxx> wrote:
From: Gen Zhang <blackgod016574@xxxxxxxxx>
[ Upstream commit 4e78921ba4dd0aca1cc89168f45039add4183f8e ]
The old_memmap flow in efi_call_phys_prolog() performs numerous memory
allocations, and either does not check for failure at all, or it does
but fails to propagate it back to the caller, which may end up calling
into the firmware with an incomplete 1:1 mapping.
So let's fix this by returning NULL from efi_call_phys_prolog() on
memory allocation failures only, and by handling this condition in the
caller. Also, clean up any half baked sets of page tables that we may
have created before returning with a NULL return value.
Note that any failure at this level will trigger a panic() two levels
up, so none of this makes a huge difference, but it is a nice cleanup
nonetheless.
[ardb: update commit log, add efi_call_phys_epilog() call on error path]
Signed-off-by: Gen Zhang <blackgod016574@xxxxxxxxx>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rob Bradford <robert.bradford@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-efi@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20190525112559.7917-2-ard.biesheuvel@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
This was already discussed in the thread that proposed this patch for
stable: please don't queue this right now, the patches are more likely
to harm than hurt, and they certainly don't fix a security
vulnerability, as has been claimed.
I've dropped this, thank you.
--
Thanks,
Sasha
